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Establishment of two nonnative parthenogenetic reptiles on Saba, Dutch Caribbean: Gymnophthalmus underwoodi and Indotyphlops braminus

2021; Linguagem: Inglês

10.31611/79

2333-2468

Matthijs P. van den Burg, Alwin Hylkema, Adolphe O. Debrot,

Fish biology, ecology, and behavior

The native herpetofauna of the Lesser Antillean island of Saba (13 km2; 17.63°N, -63.24°W) includes one snake, Alsophis rufiventris, and four species of lizards, Anolis sabanus, Iguana melanoderma, Sphaerodactylus sabanus, and Thecadatylus rapicauda (Powell et al. 2015).Here, we report the establishment of both Gymnophthalmus underwoodi Grant, 1958 and Indotyphlops braminus (Daudin, 1803) on the island.We have observed and recorded smooth-scaled tegulets (Gymnophthalmus underwoodi) since May 2020 at numerous locations across Saba (Fig. 1).We captured five individuals with snout-vent lengths of 23.12-40.64mm and preserved a single specimen (SVL = 40.64mm) that will be cataloged in the collection of the Naturalis Biodiversity Center in Leiden, The Netherlands (Fig. 2).We encountered G. underwoodi in a wide range of habitats, including gardens, dry forest, manchineel (Hippomane mancinella) forests, and grass-overgrown rocky slopes.Subcaudal scale (smooth) and head scalation morphology of the five captured individuals conformed to diagnostic characters of G. underwoodi (Cole et al. 1990, Williamson & Powell 2004, Recoder et al. 2018).We used non-native records from iNaturalist (van den Burg et al. 2020), as well as observations reported by on-island researchers to further infer the distribution of G. underwoodi (Fig. 1).Overall, G. underwoodi appears to be present across at least >50% of the island's surface, with the highest observed elevation at 711 m.Although the earliest verifiable observation dates from May 2020, given that G. underwoodi is known for rapid population growth (Daltry 2007), the island-wide distribution suggests an earlier arrival.Gymnophthalmus underwoodi has a wide native distribution, occurring both on the South American continent and throughout the Lesser Antilles (Recoder et al. 2018); however, island populations in the northern Lesser Antilles are currently believed to have been introduced (Daltry 2007, Powell et al. 2011).This report adds Saba to the list of Lesser Antillean island on which the species has been recorded: Antigua, Barbados, Barbuda, Dominica, Grenada, Guadeloupe (Basse-Terre, Grande-Terre, La Desirade, Les Saintes, Marie-Galante), Martinique, Montserrat, Nevis, St. Barthélemy, St. Kitts, St. Martin, and St. Vincent and the Grenadines (Snyder et al. 2017).On Saba, direct competition with native herpetofauna is considered unlikely.Although Sphaerodactylus sabanus and G. underwoodi both occupy habitat with abundant leaflitter, highest-activity periods are non-overlapping, with that of G. underwoodi coinciding with the heat of the day and that of S. sabanus occurring from late afternoon to midnight (Powell et al. 2015).A local resident observed the first Brahminy Blindsnake (Indotyphlops braminus) on Saba when she encountered several individuals in her garden in Windwardside from May to July 2021 (Fig. 1).These observations involved at least two different individuals based on size differences; one with a total length of ~6 cm (see https:// www.inaturalist.org/observations/54618365),the other >10 cm (Fig. 3); neither was collected.Head scalation patterns are similar to those described in Hedges et al. (2014) and coloration and head shape were typical of the